Display screen or portion thereof with an animated graphical user interface



FIG. 1 is a front view of a display screen or portion thereof with an animated graphical user interface; and,

FIG. 2 is a front view of a second image thereof.

The outermost broken lines illustrate a display screen or portion thereof and form no part of the claimed design. The remaining broken lines, illustrating portions of the animated graphical user interface, form no part of the claimed design. The appearance of the image transitions sequentially between the images shown in FIGS. 1 and 2. The process or period in which one image transitions to another forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with an animated graphical user interface, as shown and described. 